RFID tag manufacturing method with strap and substrate

ABSTRACT

In a manufacturing method of a thin and small RFID tag, an antenna metal pattern is formed on a substrate, going once around a dielectric plate, and a recess is formed on the substrate to house an IC chip. A strap on which the IC chip is mounted is connected and fastened to the substrate in the position and orientation in which the IC chip is housed in the recess.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an RFID(Radio_Frequency_IDentification) tag which exchanges information withexternal devices in a non-contact manner. Incidentally, the “RFID tag”described herein is also known as an “RFID tag inlay” among thoseskilled in the art, meaning a component laid into the RFID tag. Also,the “RFID tag” is sometimes called a “wireless IC tag.” RFID tags alsoinclude contactless IC cards.

2. Description of the Related Art

Recently, various types of RFID tag have been proposed to exchangeinformation with external devices typified by reader-writers in anon-contact manner by radio. A configuration in which an antenna patternfor wireless communications and an IC chip are mounted on a base sheetmade of plastics or paper has been proposed as a type of RFID tag (seeFor example, Japanese Patent Laid-Open Nos. 2000-311226, 2000-200332,and 2001-351082). One possible application for RFID tags of this type isto affix them to goods or the like and identify the goods by exchanginginformation about the goods with external devices.

FIG. 1 is a plan view showing an example of a RFID tag.

The RFID tag 1 shown in FIG. 1 consists of an antenna 12 installed on asheet-like base 13 made of a PET film or the like and an IC chip 11electrically connected to the antenna 12 by gold, solder, or the likeand bonded to the base 13 with an adhesive.

The IC chip 11 of the RFID tag 1 can exchange information with externaldevices by conducting wireless communications with them via the antenna12.

Although in FIG. 1, the antenna 12 of the RFID tag 1 is shown as a loopantenna, the antennas 12 for RFID tags in general are not limited tothis shape and an antenna which extends linearly in both directions froman IC chip 11 placed at the center or antennas of various other shapesmay be adopted.

RFID tags such as described above may deteriorate greatly incommunications performance if there is a metal strip or the like nearby.A RFID tag called a metal tag is known as a means of avoiding such asituation. The metal tag is a RFID tag consisting of a substratesurrounded by a metal pattern which acts as an antenna. Even if a metalstrip comes close to it, the metal tag maintains its communicationsperformance except for the part shaded by the metal strip.

Now, a conventional manufacturing method of the metal tag will bedescribed.

FIGS. 2(A) and 2(B) are perspective views of parts used in themanufacture of the metal tag.

An IC chip 11 (FIG. 2(A)) and a substrate 20 (FIG. 2(B)) for the metaltag are prepared here.

As shown in FIG. 2(A), the IC chip 11 has bumps 11 a of gold or the likeformed on its connection terminals. In FIG. 2(A), the IC chip 11 isshown upside down from the view of the IC chip 11 in FIG. 1 so that thesurface on which the bumps 11 a are formed will be visible. The IC chip11 has capability to exchange information with external devices byconducting wireless communications with them via the antenna (describedlater) (see FIG. 1).

The substrate 20 consists of a dielectric plate 21 with an antenna metalpattern 22 going around the dielectric plate 21 excluding an area 23 onwhich the IC chip 11 will be mounted, where the antenna metal pattern 22will act as an antenna after assembly.

FIGS. 3(A) to 3(C) illustrate a process chart showing an example of amanufacturing method for the metal tag.

Liquid or sheet-like underfill 24 that is a thermosetting adhesive issupplied to that area 23 of the substrate 20 on which the IC chip 11will be mounted (FIG. 3(A)). The IC chip 11 is placed on the area 23 andthen heated and pressurized together with the substrate 20 by being heldbetween a heating stage 31 and a heating head 32. Consequently, the ICchip 11 and antenna metal pattern 22 are electrically connected via thebumps 11 a and the IC chip 11 is fastened to the substrate 20 as theunderfill 24 hardens (FIG. 3(B)).

Through these processes, the RFID tag with the structure shown in FIG.3(C) is manufactured.

In the RFID tag, the IC chip 11 conducts wireless communications withexternal devices via a loop antenna which makes a round, surrounding thefront and back surfaces of the dielectric plate 21.

The RFID tag of this type is known as a metal tag. For example, even ifa metal strip is brought close to the back side of the substrate 20, thefront side on which the IC chip 11 is mounted maintains sufficientcommunications performance.

However, the RFID tag produced by the manufacturing method describedwith reference to FIGS. 2(A)-2(B) and 3(A)-3(C) is difficult to makeflat and thin because the IC chip 11 mounted on the substrate 20protrudes from the surface of the substrate 20. To solve this problem,it is at least conceivable to reduce the thickness of the substrate 20.However, in order to obtain desired performance as a loop antenna fromthe antenna metal pattern 22, it is necessary to provide some distancebetween those parts of the antenna metal pattern 22 which are located onthe front surface and back surface of the substrate. Thus, there is alimit to reducing the thickness of the substrate 20 from the viewpointof ensuring antenna performance.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstancesand provides a manufacturing method of a thin and flat RFID tag whichoffers the performance of a metal tag as well as the RFID tag producedby the manufacturing method.

A first RFID tag manufacturing method according to the present inventionhas:

a preparation step of preparing a strap which includes a connector metalpattern formed on a base and a circuit chip mounted on the base, theconnector metal pattern being used to connect the circuit chip thatconducts wireless communications via an antenna after assembly to anantenna metal pattern that acts as the antenna after assembly, andpreparing a substrate which includes the antenna metal pattern formedthereon and a recess formed on a first surface, i.e., one of front andback surfaces of the substrate, to house the circuit chip, and theantenna metal pattern being formed on the substrate such that theantenna metal pattern makes a round excluding the recess by extendingfrom the first surface to a second surface of the front and backsurfaces and back to the first surface of the substrate with both endsof the antenna metal pattern located on both sides of the recess; and

a connection step of connecting the connector metal pattern on the strapto the antenna metal pattern on the substrate by mounting the strap onthe substrate in a position and orientation in which the circuit chip onthe strap is housed in the recess formed on the substrate.

With the first RFID tag manufacturing method according to the presentinvention, the strap is connected by being mounted on the substrate inthe position and orientation in which the IC chip is housed in therecess formed on the substrate. Since the IC chip is housed in therecess, it is possible to make the RFID tag thin and flat.

In the first RFID tag manufacturing method according to the presentinvention, the preparation step may have:

a strap parts preparation step of preparing the circuit chip and a strapsheet with multiple connector metal patterns formed on the base;

a circuit chip mounting step of mounting one circuit chip on each of themultiple connector metal patterns on the strap sheet; and

a strap forming step of slicing the strap sheet with the circuit chipsmounted into individual straps each having one circuit chip and oneconnector metal pattern.

In the RFID tag manufacturing method, the circuit chip mounting step mayapply a thermosetting adhesive to that part of the strap sheet on whichthe circuit chips are to be mounted, heat and pressurize the part aftermounting the circuit chips on the part, and thereby connect the circuitchips to the connector metal patterns on the strap sheet and fasten thecircuit chips to the strap sheet.

The strap parts preparation step, circuit chip mounting step, and strapforming step make it possible to prepare the strap efficiently.

In the RFID tag manufacturing method, the preparation step may include:

a pattern forming step of forming, on a plate member where the recess isformed, a pattern portion of the antenna metal pattern on the firstsurface and a pattern portion of the antenna metal pattern on the secondsurface, such that both pattern portions correspond to the recess; and

a plating step of plating an edge of the substrate along which a patternportion that links the pattern portion on the first surface and thepattern portion on the second surface is to run.

Alternatively, in the RFID tag manufacturing method, the preparationstep may include:

a pattern forming step of forming, on a plate member where a pluralityof the recesses are formed, a first pattern portion of the antenna metalpattern on the first surface and a second pattern portion of the antennametal pattern on the second surface, such that both pattern portionscorrespond to each recess;

a piercing step of forming a through hole piercing through the platemember at such a position that corresponds to an edge of the substratealong which a pattern portion that links the first pattern portion andthe second pattern portion is to run;

a plating step of plating an inner wall of the through hole, therebyforming the pattern portion that links the first pattern portion and thesecond pattern portion; and

a substrate forming step of dividing the plate member where the antennametal pattern has been formed into individual substrates.

Employing the pattern forming steps, piercing step, plating steps andsubstrate forming step makes it possible to efficiently produce thesubstrate.

Also, in the first RFID tag manufacturing method according to thepresent invention, the connection step may apply a conductive paste toboth ends of the antenna metal pattern on both sides of the recess, heatthe strap by mounting the strap on the substrate in the position andorientation in which the circuit chip on the strap is housed in therecess, and thereby connect the connector metal pattern on the strap toboth ends of the antenna metal pattern on the substrate.

A first RFID tag according to the present invention has:

a strap that includes a connector metal pattern formed on a base andused to connect a circuit chip which, being mounted on the base,conducts wireless communications via an antenna after assembly to anantenna metal pattern which acts as an antenna after assembly; and

a substrate on which a recess is formed on a first surface, i.e., one offront and back surfaces, to house the circuit chip, and the antennametal pattern is formed making a round excluding the recess by extendingfrom the first surface to a second surface of the front and backsurfaces and back to the first surface with both ends of the antennametal pattern located on both sides of the recess,

wherein the connector metal pattern on the strap is connected to theantenna metal pattern on the substrate with the strap mounted on thesubstrate in a position and orientation in which the circuit chip on thestrap is housed in the recess formed on the substrate.

The first RFID tag according to the present invention has a structure inwhich the IC chip is housed in the recess on the substrate, making theRFID tag thin and flat.

A second RFID tag manufacturing method according to the presentinvention has:

a preparation step of preparing a tag sheet which includes a metalpattern formed on a base and acting as an antenna, and a circuit chipmounted on the base and conducting wireless communications via theantenna after assembly, and preparing a substrate which includes arecess formed on a first surface, i.e., one of front and back surfacesof the substrate, to house the circuit chip, the substrate beingsurrounded one turn over the front and back surfaces by the tag sheet,and the substrate having outer surfaces provided with an adhesive whichbonds the surrounding tag sheet and conductive material which connectsthe two ends of the metal pattern on the surrounding tag sheet;

a pressing step of pressing the first surface of the substrate againstthat position on the tag sheet where the circuit chip is housed in therecess, and thereby affixing the tag sheet to the first surface;

a bending step of bending that part of the tag sheet which sticks out ofthe substrate, along edges of the substrate; and

a re-bending process of bending the tag sheet along the edges so as tofold the tag sheet onto the second of the front and back surfaces of thesubstrate, affixing the tag sheet to the second surface, and connectingthe two ends of the metal pattern by the conductive material.

As with the first manufacturing method, with the second manufacturingmethod, since the chip is housed in the recess on the substrate, it ispossible to make the RFID tag thin and flat.

With the first manufacturing method, since there are two metal patterns,namely, the connector metal pattern and antenna metal pattern, error mayoccur in antenna length when connecting the two metal patterns with eachother as described later with reference to FIG. 11 although on rareoccasions. However, with the second manufacturing method, the entirepart of the metal pattern which acts as an antenna is formed integrallywith the tag sheet, preventing introduction of error in the antennalength during manufacture and thereby making it possible to maintainhigh communications performance.

Incidentally, the conductive material on the substrate does not causeerror in the antenna length.

Also, with the first manufacturing method, a conductive adhesive must beapplied in the process of fastening the strap to the substrate and aconductive adhesive in paste form is used after being adjusted to a lowlevel of viscosity for the convenience of application. Consequently,when the strap is pressed against the substrate, the adhesive may formclimb-up 134 a or squeeze-out 134 b as shown in FIG. 12 (FIG. 12 will bedescribed later) although on rare occasions.

On the other hand, the second manufacturing method according to thepresent invention allows the adhesive to be applied to the entiresurface of the substrate in advance, making it possible to use anadhesive with high viscosity and low flowability and eliminatingproblems described later with reference to FIG. 12.

In this way, the second RFID tag manufacturing method according to thepresent invention provides a highly reliable RFID tag manufacturingmethod which can produce thin and flat RFID tags.

In the second RFID tag manufacturing method according to the presentinvention, the pressing step and bending step may be provided eithersimultaneously or one after the other in any order.

In the second RFID tag manufacturing method according to the presentinvention, preferably the bending step bends the tag sheet by fittingthe tag sheet in a die.

Also, in the second RFID tag manufacturing method according to thepresent invention, preferably the bending step bends the tag sheet andpresses the tag sheet against the second surface using a roll.

A second RFID tag according to the present invention has:

a substrate with a recess formed on a first surface, i.e., one of frontand back surfaces; and

a tag sheet including a metal pattern which, being formed on a base,acts as an antenna and a circuit chip which, being mounted on the base,conducts wireless communications via the antenna, where the circuit chipis housed in the recess, the tag sheet is bonded to the substrate bysurrounding the front and back surfaces of the substrate one turn, andboth ends of the metal pattern are connected to the tag sheet.

As described above, the present invention provides a thin and flat RFIDtag.

Furthermore, the second RFID tag manufacturing method according to thepresent invention provides the second RFID tag which is more reliablethan the first RFID tag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an example of a RFID tag;

FIGS. 2(A) and 2(B) are perspective views of parts used in themanufacture of a metal tag;

FIGS. 3(A) to 3(C) are diagrams illustrating a process chart showing anexample of a manufacturing method for the metal tag;

FIGS. 4(A) and 4(B) are perspective views showing parts used in a firstRFID tag manufacturing method;

FIG. 5 is a process chart showing a strap manufacturing method;

FIGS. 6(A) through 6(C) are diagrams showing a first process in amanufacturing method of a substrate;

FIGS. 7(A) and 7(B) are diagrams showing a second process and a thirdprocess in the manufacturing method of the substrate, respectively;

FIG. 8 is a diagram showing a fourth process in the manufacturing methodof the substrate;

FIGS. 9(A) to 9(C) are diagrams illustrating a process chart showing theRFID tag manufacturing method which uses the strap and substrate shownin FIGS. 4(A) and 4(B);

FIG. 10 is a sectional view of a RFID tag produced by the RFID tagmanufacturing method shown in FIGS. 9(A) to 9(C);

FIG. 11 is a diagram showing one of the problems encountered on rareoccasions with RFID tags produced by the RFID tag manufacturing methodshown in FIGS. 4(A) to 9(C);

FIG. 12 is a diagram showing another problem encountered on rareoccasions with RFID tags produced by the RFID tag manufacturing methodshown in FIGS. 4(A) to 9(C); and

FIG. 13 is a diagram showing an embodiment of a second RFID tagmanufacturing method according to the present invention and a RFID tagproduced by the second manufacturing method.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below.

FIGS. 4(A) and 4(B) are perspective views showing parts used in a firstRFID tag manufacturing method.

The first manufacturing method prepares a strap 120 shown in FIG. 4(A)and a substrate 130 shown in FIG. 4(B).

The strap 120 shown in FIG. 4(A) includes a connector metal pattern 122formed on a base 121 made of a PET film or the like and an IC chip 11mounted on the base 121 and electrically connected with the connectormetal pattern 122. As is the case with the IC chip shown in FIG. 2(A),the IC chip 11 has gold bumps formed on it and has capability to conductwireless communications with external devices via an antenna describedlater (see FIG. 1).

The substrate 130 in FIG. 4(B) includes a dielectric plate 131 on whicha recess 133 is formed to house the IC chip 11 and an antenna metalpattern 132 is formed making a round excluding the recess 133 by goingaround front and back surfaces.

Next, a manufacturing method of the strap 120 shown in FIG. 4(A) will bedescribed.

FIG. 5 is a process chart showing the strap manufacturing method.

First, a long strap sheet 120A is prepared.

As shown in Part (A-1) of FIG. 5, the strap sheet 120A includes multipleconnector metal patterns 122 formed on a long base 121 made of a PETfilm or the like. Part (A-2) of FIG. 5 is a sectional view of oneconnector metal pattern on the strap sheet 120A.

The connector metal pattern 122 consists of two strips, between which anIC chip is mounted.

Next, liquid or sheet-like underfill 123—which is a thermosettingadhesive—is supplied to the IC chip mounting positions of the connectormetal patterns 122 formed on the strap sheet 120A (see Parts (B-1) and(B-2) of FIG. 5). In this case, as shown in Part (B-2) of FIG. 5, liquidunderfill 123 is dripped through a nozzle 33.

Next, the IC chips 11 are placed on the underfill 123 (see Parts (C-1)and (C-2) of FIG. 5), and heated and pressurized by being held betweenthe heating stage 31 and heating head 32 (see Parts (D-1) and (D-2) ofFIG. 5). Consequently, the IC chips 11 are electrically connected withthe connector metal patterns 122 via bumps 11 a, and then fastened tothe strap sheet 120A as the underfill 123 hardens.

Furthermore, the strap sheet 120A is diced by blanking or cutting intoindividual straps 120 containing an IC chip 11 and a connector metalpattern 122 (see FIG. 4(A)).

Next, there will be described a manufacturing method of the substrate130 shown in FIG. 4(B).

The manufacturing method of the substrate 130 is a method of efficientlymanufacturing multiple substrates 130 and composed of two or moreprocesses. There will be described below an example that threesubstrates 130 are manufactured.

FIGS. 6(A) through 6(C) are diagrams showing a first process in themanufacturing method of the substrate 130.

In this process, there are formed that pattern portions of the antennametal pattern 132 of the substrate 130 which are to be fixed on thefront and back surfaces of the dielectric plate 131, except for patternportions to run along the both edges of the dielectric plate 131.

First, as shown in FIG. 6(A), the front and back surfaces of thedielectric plate 131 are covered with metal foil for forming a metalpattern. A plate member 130A having three recesses 133 formed on onesurface thereof is thus prepared. In the following description, thesurface where the three recesses 133 are formed will be referred to as“top surface,” while the other surface opposite the top surface will bereferred to as “bottom surface.”

Subsequently, as illustrated in cross-sectional and top views shown inFIG. 6(B), that parts of the antenna metal pattern 132 shown in FIG.4(B) which serve as pattern portions 132 a extending with the recesses133 interposed between is formed on the top surface of the plate member130A for the amount covering three substrates 130. As shown in FIG.6(B), pattern portions 132 a spanning adjacent substrates 130 are eachintegrally formed as a continuous line. Incidentally, the patternportions 132 a are formed in such a manner that the metallic foilcovering the surface of the plate member 130A, except for portionscorresponding to the pattern portions 132 a, is removed by etching.

Next, as illustrated in cross-sectional and top views shown in FIG.6(C), that part of the antenna metal pattern 132 shown in FIG. 4(B)which serves as pattern portions 132 b for three substrates 130 isformed on the bottom surface of the plate member 130A, opposite the topsurface where the recesses 133 are formed. The pattern portions 132 bare integrally formed as a continuous line covering the three substrates130. The pattern portions 132 b are also formed by etching.

This first process is efficient because the pattern portions 132 a forthree substrates 130 are formed on the top surface at a time by thefirst etching, and the pattern portions 132 b for three substrates 130are formed on the bottom surface at a time by the second etching.

Upon completion of the formation of the pattern portions, themanufacturing method of the substrate 130 proceeds to the next process.

FIGS. 7(A) and 7(B) are diagrams showing a second process and a thirdprocess in the manufacturing method of the substrate 130, respectively.

In the second process, as illustrated in cross-sectional and top viewsshown in FIG. 7(A), a through hole 130A_1 piercing through the platemember 130A is formed at a position that corresponds to each of bothedges of the dielectric plate 131 along which the antenna metal pattern132 is to run in the substrate 130 shown in FIG. 4(B). The hole 130A_1is formed for each of the three substrates 130.

Subsequently in the third process, as illustrated in cross-sectional andtop views shown in FIG. 7(B), an inner wall of each through hole 130A_1is plated with metal of the same kind as the metal forming each patternportion. In this way, in the third process, there is formed a patternportion 132 c that runs along each of the edges and links the patternportion 132 a on the top surface and the pattern portion 132 b on thebottom surface, so that the antenna metal pattern 132 is completed.

In these second and third processes, plating an inner wall of onethrough hole 130A_1 forms two pattern portions 132 c of the respectiveadjacent antenna metal patterns 132 at the same time, which isefficient.

After the antenna metal pattern 132 for each of the three substrates 130is thus formed, each substrate 130 as shown in FIG. 4(B) is completed inthe next process.

FIG. 8 is a diagram showing a fourth process in the manufacturing methodof the substrate 130.

In the fourth process, as illustrated in cross-sectional and top viewsshown in FIG. 8, the plate member 130A where the three antenna metalpatterns 132 are formed is cut into three pieces along cutting-planelines passing through the plated through holes 130A_1 and then trimmed.Thus, three substrates 130 as shown in FIG. 4(B) are completed.

Incidentally, there has been described as an example with reference toFIG. 6(A) through FIG. 8, the manufacturing method in which the patternportion 132 a on the top surface and the pattern portion 132 b on thebottom surface are formed and then, the through hole 130A_1 is formedand plated. However, the invention is not limited to this example. Themanufacturing method of the substrate may be such a method that thethrough hole 130A_1 is formed and plated first and then, the patternportion 132 a on the top surface and the pattern portion 132 b on thebottom surface are formed.

Next, description will be given of a RFID tag manufacturing method whichuses the strap 120 thus prepared (shown in FIG. 4(A)) and the substrate130 thus prepared separately (shown in FIG. 4(B)).

FIGS. 9(A) to 9(C) illustrate a process chart showing the RFID tagmanufacturing method which uses the strap 120 and substrate 130 shown inFIGS. 4(A) and 4(B).

First, a thermosetting conductive adhesive 134 is supplied to both endsof the antenna metal pattern 132 on both sides of the recess 133 on thesubstrate 130 through a dispenser nozzle 34 (FIG. 9(A)). A conductivepaste for connection may be printed instead of the supply through thenozzle 34.

Next, the strap 120 is turned upside down and mounted on the substrate130 with the antenna metal pattern 132 on the substrate 130 aligned withthe IC chip 11 on the strap 120 (FIG. 6(B)). As the conductive adhesiveis hardened by heating, the connector metal pattern 122 on the strap 120and the antenna metal pattern 132 on the substrate 130 are electricallyconnected with each other with the IC chip 11 housed in the recess 133on the substrate 130 and the strap 120 is fastened to the substrate 130(FIG. 9(C)).

In the process in FIG. 9(C), in addition to heating, the substrate 130and strap 120 may be pressurized by being pinched

In the RFID tag thus manufactured, the connector metal pattern 122 onthe strap 120 and the antenna metal pattern 132 on the substrate 130form a loop antenna which makes a round, surrounding the front and backsurfaces of the dielectric plate 131 and via which the IC chip 11conducts wireless communications with external devices.

FIG. 10 is a sectional view of a RFID tag produced by the RFID tagmanufacturing method.

The IC chip 11 is housed in the recess 133 on the substrate 130, makingthe RFID tag thinner and flatter than the conventional example describedwith reference to FIGS. 2(A)-2(B) and 3(A)-3(C).

FIG. 11 is a diagram showing one of the problems encountered on rareoccasions with RFID tags produced by the RFID tag manufacturing methodshown in FIGS. 4(A) to 9(C).

During hardening of the conductive adhesive 134 (see FIG. 6(A)) when orafter the strap 120 is mounted on the substrate 130, the strap 120 maytilt on the substrate 130 as shown in FIG. 11. If the strap 120 ismounted in a tilted condition, the loop antenna formed by the connectormetal pattern 122 on the strap 120 and the antenna metal pattern 132 onthe substrate 130 will deviate from its normal length, which may affectcommunications functions.

FIG. 12 is a diagram showing another problem encountered on rareoccasions with RFID tags produced by the RFID tag manufacturing methodshown in FIGS. 4(A) to 9(C).

FIG. 12 is an enlarged view of a bonded portion between the substrate130 and strap 120.

With the manufacturing method shown in FIGS. 9(A)-9(C), the conductiveadhesive 134 in paste form (see FIG. 9(A)) is used when mounting andfastening the strap 120 onto the substrate 130, but it is difficult toaccurately control application quantity of the conductive adhesive 134,which is in paste form, in the process shown in FIG. 9(A). A littleexcess application may cause the conductive adhesive to form climb-up134 a above the strap 120 or squeeze-out 134 b inside the recess 133 asshown in FIG. 12. When printing is used by affixing paper to the RFIDtag after the process in FIG. 9(A)-9(C), climb-up 134 a may cause printdefects. Also, squeeze-out 134 b inside the recess 133 may cause a shortcircuit with the IC chip 11, resulting in a malfunction.

RFID tags which encounter any of the problems described with referenceto FIGS. 11 and 12 may be removed in the process of inspection, but itis preferable to increase manufacturing reliability.

Next, description will be given of a RFID tag manufacturing method whichcan not only produce thin and flat RFID tags, but also increasereliability. Also, description will be given of the RFID tag produced bythe manufacturing method.

FIG. 13 is a diagram showing an embodiment of a second RFID tagmanufacturing method according to the present invention and a RFID tagproduced by this manufacturing method.

First, a substrate 310 and a tag sheet 320 are prepared (Parts (A) and(B) of FIG. 13).

The substrate 310 consists of a plastic plate 311 with a hole 314 (seePart (C) of FIG. 13) formed to house an IC chip 11. Furthermore, anadhesive 312 is applied to around the substrate 310, and a conductivematerial 313 such as a conductive sheet or conductive adhesive isapplied to a seam of an antenna.

The tag sheet 320 consists of a metal pattern 322 which, being formed ona base 321 made of a PET film or the like, acts as an antenna aftermanufacture and an IC chip 11 mounted on the base 321 bythermocompression bonding or by solder reflow.

Incidentally, the metal pattern 322 has a design different from that ofthe metal pattern 132 (see FIG. 4(B)) according to the above embodiment.This is because an optimal pattern is selected according to combinationwith the IC chip 11, uses, and the like.

Next, a first surface of the substrate 310 on which the recess 314 isformed is pressed against that position on the tag sheet 320 where theIC chip 11 is housed in the recess 314 on the substrate 310, andconsequently the tag sheet 320 is affixed to the first surface with theadhesive 312 applied to the substrate 310 (Part (C) of FIG. 13).

The tag sheet 320 with which the first surface of the substrate 310connected is fitted in a die 350 in which a recess 351 of an appropriatesize is formed, and consequently, that part of the tag sheet 320 whichsticks out of the substrate 310 is bent along edges of the substrate 310(Part (D) of FIG. 13).

Instead of the processes in Parts (C) and (D) of FIG. 13, the tag sheet320 may be fitted alone in the die 350 and bent as shown in Part (D) ofFIG. 13, before mounting and bonding the substrate 310 onto it.Alternatively, the tag sheet 320 positioned on the die 350 may be pushedinto the recess 351 of the die 350 by the substrate 310 to mount thesubstrate 310 on the tag sheet 320 and bend the tag sheet 320simultaneously.

After being processed to the condition shown in Part (D) of FIG. 13, thetag sheet 320 is bent along the edges of the substrate 310 by a roller360 so as to fold down onto the second surface which is opposite thefirst surface of the substrate 310 on which the recess 314 is formed,the tag sheet 320 is bonded to the second surface, and both ends of themetal pattern 322 on the tag sheet 320 are connected by the conductivematerial 313 (Part (E) of FIG. 13).

Through these processes, the RFID tag with the structure shown in Part(F) of FIG. 13 is manufactured.

The manufacturing method shown in FIG. 13 not only produces thin andflat RFID tags as with the embodiment described earlier, but alsoeliminates the problem of increased antenna length described withreference to FIGS. 11 and 12 as well as further improves reliability.

Also, whereas the manufacturing method described earlier needs theprocess of blanking or cutting the strap sheet 120A into straps 120, themanufacturing method shown in FIG. 13 eliminates the need for such aprocess. Also, the manufacturing method shown in FIG. 13 does not needthe process of forming a metal pattern on a substrate, which is morecomplex and costly than the process of applying an adhesive orconductive material on the substrate. In this way, the manufacturingmethod shown in FIG. 13 requires a smaller number of processes and costsless than the manufacturing method described earlier.

1-6. (canceled) 7: An RFID tag comprising: a strap that includes aconnector metal pattern formed on a base and used to connect a circuitchip which, being mounted on the base, conducts wireless communicationsvia an antenna after assembly to an antenna metal pattern which acts asan antenna after assembly; and a substrate on which a recess is formedon a first surface, i.e., one of front and back surfaces, to house thecircuit chip, and the antenna metal pattern is formed making a roundexcluding the recess by extending from the first surface to a secondsurface of the front and back surfaces and back to the first surfacewith both ends of the antenna metal pattern located on both sides of therecess, wherein the connector metal pattern on the strap is connected tothe antenna metal pattern on the substrate with the strap mounted on thesubstrate in a position and orientation in which the circuit chip on thestrap is housed in the recess formed on the substrate. 8-11. (canceled)12: An RFID comprising: a substrate with a recess formed on a firstsurface, i.e., one of front and back surfaces; and a tag sheet includesa metal pattern which, being formed on a base, acts as an antenna, and acircuit chip which, being mounted on the base, conducts wirelesscommunications via the antenna, where the circuit chip is housed in therecess, the tag sheet is bonded to the substrate by surrounding thefront and back surfaces of the substrate one turn, and both ends of themetal pattern are connected to the tag sheet.